There's nothing wrong in participating in airdrops (and in your own case, STILL participating). However, the nag there is that airdrops won't reward you much as bounties would do. How much tokens can airdrops really give out to each promoter? Not much of course. And most times those tokens are even worth less or nothing at all. The only good thing about airdrops is that you don't get to expose your data much while registering for them. Otherwise, stick to bounties specially signature bounties.